This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The characteristic symptoms induced by a plant virus on its host result from the interactions between viral and host gene products. While it has been proven to be relatively easy to identify plant virus genes responsible for symptom development or for host range determination, the mechanisms by which these gene products elicit specific responses or influence host range remain to be fully understood. My research attempts to characterize the viral and plant genes responsible for the hypersensitive response elicited in Nicotiana gossei by Tobacco mosaic virus and the systemic cell death induced in Nicotiana excelsior by Tobacco rattle virus. The information gained from these host-pathogen systems will provide a greater understanding of how these viruses elicit different cell death responses and new insights into the mechanisms of plant virus-induced symptoms. Furthermore, this project exposes undergraduate students to the areas of molecular biology, molecular plant pathology, and the beneficial uses of biotechnology in plant protection.